VVT Cam .......... or ......... LS3 Conversion

[SSE 4 2SS]

Originally Posted by PQ

Now...... Let me continue my psycosis....... So, wouldn't my smaller primaries be more effective becasue I lose much less boost? I mean up to a certain power anyway. And not anything I will be going for. Not over 600 rwhp.

Attachment 216095

as above, smaller primaries mean more resistance to exhaust flowing, and it possible to see very high resistance numbers... The exhaust flow is high velocity, intake is relatively low velocity, hence the valve size... If you have 10+ lbs of resistance, and seven lbs of boost, which direction is the gas going to flow,,,, back into the intake... Then the exhaust valve closes, and the back flow stops, and the rest of the cylinder filling is with fresh air...

[PQ]

Originally Posted by SSE 4 2SS

I understand one, I found an article, and went and read it...too much to post here, and I'm on my iPad, so it's hard to copy and paste, but I'll do so tomorrow when/if I make it put to the rig... Weather is sketchy...

there are tremendous amounts of variables, exhaust back pressure, cylinder fill efficiency, overlap, duration etc....

In a nut shell, as was just mentioned, it is an air pump, so, let it breath,,,

Good flowing exhaust, proper LSA, narrow in the boosted application, limit the duration, and wala, amazing power....

the exhaust can cause back pressure, which you want some, but if it reaches say 10 lbs of resistance, and you are pushing 7 lbs, and there is some overlap, both valves open at the same time, then the air will go to the point of least resistance... In this case the intake side,,,, with exhaust gases... If this is a 30 degree overlap in a 280 degree duration cam, then you end up with roughly a 85 percent efficiency in cylinder filling with fresh air...

The same can be said for velocities... Exhaust valves are smaller, and therefore the same volume, or actually more volume has to flow through a smaller are! So velocities are much higher... Leading to back pressure in a restrictive exhaust system...
If you free flow the exhaust, and limit the overlap via either duration and/or LSA, then you can achieve higher cylinder filling efficiencies with fresh air... And create more power.

Wow, now my head hurts...

I'm actually following pretty good on all of this.

Doesn't make the decision any easier, but at least I know what I'm looking at. hahaha

[PQ]

Originally Posted by SSE 4 2SS

as above, smaller primaries mean more resistance to exhaust flowing, and it possible to see very high resistance numbers... The exhaust flow is high velocity, intake is relatively low velocity, hence the valve size... If you have 10+ lbs of resistance, and seven lbs of boost, which direction is the gas going to flow,,,, back into the intake... Then the exhaust valve closes, and the back flow stops, and the rest of the cylinder filling is with fresh air...

And subsequently less power.

2 steps forward, three steps back so to speak.'

[SSE 4 2SS]

Originally Posted by PQ

And subsequently less power.

2 steps forward, three steps back so to speak.'

Ju got it mhun...though there is more to it, that's the cliff notes...Though two forward and one back is closer to the truth...

[PQ]

Originally Posted by SSE 4 2SS

Ju got it mhun...though there is more to it, that's the cliff notes...Though two forward and one back is closer to the truth...

Right.

So then I guess I should be asking what cam would be best for my headers and blower.

Maybe VVT would be the way to go with my restrictions anyway?

[SSE 4 2SS]

Look at it in my case, if I have a rump rump cam, and lots of overlap, and a restrictive exhaust, then my boost is circulating around and coming out of the exhaust valve as boost enhancement, t there is a point of diminishing returns,.. What I create essentially is a high bypass turbo engine, great for jets, not so much for cars...they force feed themselves through velocity, we force feed through exhaust gases...if my exhaust gas and my boost become the same thing, and it works, then I would have created perpetual energy, which isn't happening...so, I loose power with small LSA, and lots of overlap,,, the trade off to large duration is higher lifts, which create other problems, li,e was mentioned earlier, the valve kissing the piston.... Not good...Tis a fine balancing act we are taking on... Which is why I have such a good and knowledgeable builder...

[SSE 4 2SS]

Originally Posted by PQ

Right.

So then I guess I should be asking what cam would be best for my headers and blower.

Maybe VVT would be the way to go with my restrictions anyway?

This is a question for someone way smarter than I am...

[PQ]

Originally Posted by SSE 4 2SS

Look at it in my case, if I have a rump rump cam, and lots of overlap, and a restrictive exhaust, then my boost is circulating around and coming out of the exhaust valve as boost enhancement, t there is a point of diminishing returns,.. What I create essentially is a high bypass turbo engine, great for jets, not so much for cars...they force feed themselves through velocity, we force feed through exhaust gases...if my exhaust gas and my boost become the same thing, and it works, then I would have created perpetual energy, which isn't happening...so, I loose power with small LSA, and lots of overlap,,, the trade off to large duration is higher lifts, which create other problems, li,e was mentioned earlier, the valve kissing the piston.... Not good...Tis a fine balancing act we are taking on... Which is why I have such a good and knowledgeable builder...

It's good you try and understand it all too. I try and do the same thing. Of course so far I have done all of my mods myself. But the cam I may let someone do it. Not sure yet.

[SSE 4 2SS]

Originally Posted by Dangeruss

I'm with you on that. This may sound dumb, but I honesty wanted the cam for the lope!

Nothing dumb about it, you got what you wanted and what you paid for... Your car, your money, your vision...and you got great vision with that beauty...

[SSE 4 2SS]

Originally Posted by PQ

It's good you try and understand it all too. I try and do the same thing. Of course so far I have done all of my mods myself. But the cam I may let someone do it. Not sure yet.

The install you can do, just try to find someone reputable to help you with proper selection, not just someone wanting to boost sales... Pun may be intended.... Just haven't figured that out yet...

[Huggerorange73]

PQ...as a good starting point, give Comp Cams a call. At the least they can give you a starting point based around your set up.

Then call every vendor on the site and get their take....compile all the research/info and make a choice.

But do the damn suspension first!

[klatterblast]

Its all very confusing but i let a good performance shop (thunder racing) pick my cam its a blower cam with a little lope and good power to redline and it is perfect for a stock converter. your headers are fine at 1 3/4 if you want more power after the cam install all you have to do is pulley down on your magnacharger . 550 rwhp is all you want or you will have to upgrade your fuel system. You dont need a huge cam with a supercharger , you can always add boost to get where you want. Alan futral in walker la. is well known for custom cams also maybe call him .

[Scott@Bjorn3D]

Originally Posted by Milk 1027

VVT cam from MAST

VVT from Mast, I agree. GM Performance mag did a write up last year on these guys CAM's and the different stages they make. If you want to go all out get their stage III and HEADS. You will easily be over 600HP with that.

And I thnk they know what they are doing. They sell a complete package with Maggie making 800HP on a bored L99. Sticking with their CAM and Heads on a non bored L99 you should still have about 600HP at the back wheels.

Here is a good CAM: http://www.mastmotorsports.com/2010/...VT Cams&id=227

Or what the hell, trade you L99 in for one of these L99's http://www.mastmotorsports.com/2010/...Drop In&id=121

It's only money and your are getting some tax money back. Now you would have 6.8 Liters and kill Chris. Plus you would have 18 month warranty on the new motor and blower.

[Supercharged SS]

Thanks God I am done worry about this. I just left the car with Ted and said call me when its done. I don't know what to think anymore!


PQ, when I was debating this I came up with this. The LS3 conversion is more $$ to do but I believe that you can rev the motor higher, thus getting more peak hp ( which is not really useable on the street), and since you need to change more parts you can get more durable parts. So ls3 conversion = more peak hp + better parts and durability

Staying with a VVT cam will cost less and provide you with the better low end tq but less of a peak number which you don't seem to worry about. Can you tell the difference between 540 rwhp and 570 rwhp? I don't think I could.

Maybe someone with a graph can explain the difference in what the curves will be.

Has anyone with a Maggied done a blower VVT cam.

When I went with Ted's LS3 conversion and blower cam I also changed from 1 3/4" headers to 2". The rwhp went from 545 to 625. Rwtq went from 553 to around 600, maybe like 598, its late. But with the addition of that we had to drop a pulley size to regain the 2 lb.s of boost.

I hope that I did my part in adding nothing uselful and confusing you more.

Lets see how long it takes for someone who actually knows this stuff to crap on my theory!